1. Field of Invention
The present invention relates to a red photosensitive resin composition for a color filter and a color filter formed by the red photosensitive resin composition. More particularly, the present invention relates a red photosensitive resin composition for a color filter having excellent brightness, contrast, development resistance, and temporal stability of sensitivity.
2. Description of Related Art
The color filters have been widely applied in the color liquid crystal display device, color fax machine, color recorder and other applications. There is an improvement in the market requirements of the color liquid crystal display device. Thus, the producing methods of the color filters are tended to variety for satisfying the aforementioned market requirements.
Red, green and blue pixels are formed on a glass substrate to produce the color filters by dyeing method, printing method, electrodeposition method, pigment dispersing method and the like. For further improving contrast of the color filter, shielding layer (black matrix) was disposed between pixels in pixel color layer.
In conventionally color filter, diketo-pyrrolo-pyrrole pigment was used for red pigment in a photosensitivity resin composition of red pixels. Conventionally diketo-pyrrolo-pyrrole pigment and C.I. Pigment Red 254 can further improve brightness of the color filter. Japanese Patent publication No. 1999-231516 and international publication No. 2009-144115 further disclosed a brominated-diketo-pyrrolo-pyrrole pigment for new red pigment.
In recent years, there are requirements of high brightness and high contrast. Thus, primary particle size of the brominated-diketo-pyrrolo-pyrrole pigment is further decreased for meeting the requirements of high brightness and high contrast.
Moreover, for satisfying the aforementioned high brightness and high contrast, a concentration of the diketo-pyrrolo-pyrrole pigment is needed to increase in the photosensitivity resin composition. However, when the high concentration diketo-pyrrolo-pyrrole pigment mixed with the conventional photo initiator, the photosensitivity resin composition has defects of bad temporal stability of sensitivity.
Furthermore, a pigment ratio of the photosensitivity resin composition is increased with the requirement of higher color saturation. However, when the pigment ratio is increased, a relatively amount of an alkali-soluble resin and a photosensitivity monomer is decreased, thereby lowing curing degree after exposing, further decreasing development resistance.
Accordingly, there is a need to improve the aforementioned disadvantages when the diketo-pyrrolo-pyrrole pigment is used for increasing the brightness and contrast of the color filter and simultaneously improving the temporal stability of sensitivity and development resistance for the requirements of the color filter.